Total serum and ionized magnesium concentrations in healthy and hospitalized dogs.

OBJECTIVE: To determine if an association between ionized magnesium (iMg) and total magnesium (tMg) exists in healthy and hospitalized dogs admitted through an emergency service and to assess the associations between iMg and tMg with total protein, albumin, ionized calcium, and total calcium. DESIGN: Prospective cohort study. SETTING: Veterinary teaching hospital. ANIMALS: Sixty-nine dogs were enrolled. The healthy control group (group 1) included 24 dogs, and the hospitalized group (group 2) included 45 dogs. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: For both groups, signalment, a venous blood gas, and serum biochemistry were obtained. In addition, the presumptive diagnosis was recorded for group 2. Blood was obtained prior to any therapeutic interventions. Group 1 tMg was within the reference interval (RI), and the values for iMg were used to provide a healthy group range (HGR) of 0.44-0.50 mmol/L. Group 2 tMg was within the RI, but iMg was below the calculated HGR range (group 2 median iMg = 0.4 mmol/L; range = 0.27-0.70). There was a significant positive correlation between iMg and tMg in each group (group 1: r = 0.6713, P = 0.0003; group 2: r = 0.5312, P = 0.0002). Ionized Mg and tMg were not significantly associated with any of the other evaluated variables in either group. CONCLUSIONS: Ionized Mg and tMg were significantly associated in both healthy and hospitalized dogs, but the relationship was weaker in the hospitalized dogs compared with the healthy population. For hospitalized dogs, the relationship was weak enough to question the validity of using iMg and tMg interchangeably to track magnesium status.

Successful Management of Severe Bromethalin Toxicosis in a Dog.

ABSTRACT The use of bromethalin rodenticides has risen since 2011, and in some states, it is the most common rodenticide ingestion reported to poison control. Although intravenous lipid emulsion (ILE) has been previously reported to lower serum desmethylbromethalin levels in an asymptomatic dog, and repeated mannitol has been investigated in a laboratory setting, there are no published reports of successful treatment of symptomatic bromethalin toxicosis in dogs. A 9 yr old castrated male Norwich terrier was evaluated for obtunded mentation, seizures, cranial nerve deficits, and tetraparesis secondary to bromethalin toxicosis. The patient was treated with ILE, mannitol, and ginkgo biloba and returned to normal neurological function. Bromethalin exposure was confirmed by serum desmethylbromethalin levels. Previous literature indicates that the prognosis for patients who suffer from symptomatic bromethalin toxicosis is poor to grave, and the return to normal neurological function after severe toxicosis has not been reported. ILE, mannitol, and ginkgo biloba are readily available and relatively inexpensive, and in combination may be of benefit in symptomatic bromethalin intoxication.

Blood Gas Analyzers.

Acid-base and respiratory disturbances are common in sick and hospitalized veterinary patients; therefore, blood gas analyzers have become integral diagnostic and monitoring tools. This article will discuss uses of blood gas analyzers, types of samples that can be used, sample collection methods, potential sources of error, and potential alternatives to blood gas analyzers and their limitations. It will also discuss the types of analyzers that are available, logistical considerations that should be taken into account when purchasing an analyzer, and the basic principles of how these analyzers work.

Perioperative Acid-Base and Electrolyte Disturbances.

Obtaining and interpreting blood gas and electrolyte levels is essential in the management of perioperative veterinary patients. Metabolic and electrolyte alterations are common in critically ill surgical patients, and can lead to alterations in cardiovascular function, neurologic status, respiratory function, and even response to various drug therapies. Several common perioperative conditions are discussed in this article, including metabolic disturbances, electrolyte abnormalities (hyponatremia and hypernatremia, hyperkalemia), and respiratory abnormalities.

Pulse oximetry and capnometry.

Respiratory dysfunction is common in veterinary patients and various techniques have been developed to rapidly and accurately monitor pulmonary gas exchange. Pulse oximetry and capnometry are tools that allow for continuous evaluation of pulmonary function. Methodology, indications, and limitations of pulse oximetry and capnometry are discussed in this article. Both techniques are useful for monitoring critically ill or anesthetized patients; however, limitations to their use exist which underscore the need for intermittent arterial blood gas analysis.

Survival after anaphylaxis induced by a bumblebee sting in a dog.

A 3.5 yr old castrated male miniature schnauzer was referred with a history of collapse after a bee sting to the left hind limb. At the time of presentation, 14 hr after the sting, the dog was hypotensive, comatose, seizuring, and had a brief period of cardiac arrest. Over the following 48 hr, the dog developed azotemia, severely elevated liver enzyme levels, hypertension, hematochezia, hematemesis, and disseminated intravascular coagulation (DIC). The dog's neurologic status improved slowly, but significant behavioral abnormalities remained. The dog was discharged after 7 days with ongoing polyuria, polydipsia, and behavioral changes. The polydipsia and polyuria resolved within a few days, but the behavioral changes continued for 6 wk. Reports of anaphylaxis from any cause are sparse in the veterinary literature. This is the first report of suspected anaphylaxis following a bee sting. There are no previous reports of behavioral changes after physical recovery from anaphylaxis.

Anticoagulant rodenticide screening in dogs: 123 cases (1996-2003).

OBJECTIVE: To identify dogs with anticoagulant rodenticide (AR) screens submitted, determine whether detected concentrations of the anticoagulants correlated with severity of clinical signs for dogs with positive results on AR screens, and identify the most common disease processes present and the prognosis for those with negative AR screens. DESIGN: Retrospective case series. ANIMALS: 123 dogs. PROCEDURES: History, signalment, clinical signs, physical examination findings, PCV, total solids concentration, prothrombin time, activated partial thromboplastin time, platelet count, AR concentrations, duration of hospitalization, blood products administered, final diagnosis, and outcome were recorded from medical records of dogs that underwent AR toxicology screenings. RESULTS: 75 of 123 (60.9%) dogs tested positive for AR. Dogs tested positive for brodifacoum, diphacinone (also called diphenadione), and chlorophacinone. Dogs with positive AR screenings weighed significantly less, received significantly more fresh frozen plasma, had significantly longer initial prothrombin time, and were significantly more likely to survive, compared with those with negative screens. Anticoagulant rodenticide concentrations ranged from trace amounts to 1,120 parts per billion and were not correlated with any recorded parameter. The most common conditions diagnosed in the 48 dogs with negative screens included neoplasia in 15 (31.3%), immune-mediated disease in 7 (14.6%), and gastrointestinal bleeding in 5 (10.4%) dogs. CONCLUSIONS AND CLINICAL RELEVANCE: AR concentrations were not correlated with severity of clinical signs or the degree of prolongation of coagulation times in this series of patients. Patients with severe coagulopathies but negative results of AR screening had a poor prognosis, with neoplasia as the most common diagnosis. Anticoagulant rodenticide intoxication had the best prognosis, with a survival rate of 98.7% in this study.

Anticoagulant effects of low-molecular-weight heparins in healthy cats.

BACKGROUND: Low-molecular-weight heparin (LMWH) has potential benefit in cats at risk for thromboembolic disease. However, LMWH pharmacokinetics has not been characterized in the cat. Drug effect with LMWH may be evaluated with analysis of factor Xa inhibition (anti-Xa) or thromboelastography (TEG). HYPOTHESIS: Administration of LMWH at previously recommended dosages and schedules to healthy cats will result in inhibition of factor Xa and hypocoagulable TEG. ANIMALS: In vivo research with heparin was performed in 5 purpose-bred cats. METHODS: In a prospective study with randomized crossover design, heparin or placebo was administered. Treatments were unfractionated heparin (UFH), 250 IU/kg q6h; dalteparin, 100 IU/kg q12h; enoxaparin, 1 mg/kg q12h; or 0.9% saline, 0.25 mL/kg q6h. Each drug was administered for 5 consecutive days followed by a minimum washout of 14 days. Baseline and post-treatment analyses included anti-Xa, TEG, and prothrombin time/activated partial thromboplastin time. RESULTS: Mean anti-Xa activity 4 hours after enoxaparin (0.48 U/mL) approached the human therapeutic target (0.5-1.0 U/mL); however, mean trough anti-Xa activity was below detection limits. Mean anti-Xa activity 4 hours after dalteparin was lower, and only 1 cat attained therapeutic target at a single time point. Cats receiving UFH attained target anti-Xa activity and changes in TEG at trough and 4 hours. CONCLUSIONS: Cats have rapid absorption and elimination kinetics with LMWH therapy. On the basis of pharmacokinetic modeling, cats will require higher dosages and more frequent administration of LMWH to achieve human therapeutic anti-factor Xa activity of 0.5-1 U/mL. Peak anti-Xa activity is predicted at 2 hours after administration of LMWH.

Risk factors, prognostic indicators, and outcome of pyothorax in cats: 80 cases (1986-1999).

OBJECTIVE: To identify risk factors associated with development of pyothorax in cats, assess survival rates for cats that are treated, determine prognostic indicators, and determine recurrence rates. DESIGN: Retrospective study. ANIMALS: 80 cats with pyothorax and 212 control cats. PROCEDURE: History; month of evaluation; physical examination findings; results of hematologic, serum biochemical, and retrovirus testing; radiographic findings; outcome; recurrence rate; and necropsy findings were recorded. For control cats, age, sex, breed, indoor versus outdoor status, vaccination history, and single- versus multi-cat household status were recorded. RESULTS: Cats from multi-cat households were 3.8 times as likely (95% confidence interval, 1.9 to 8.2) to develop pyothorax, compared with cats from single-cat households. Indoor or outdoor status was not a risk factor. Cats with pyothorax were significantly younger (mean, 3.83 +/- 3.43 years) than controls (mean, 5.62 +/- 5.27 years). Nonsurvivors had significantly lower heart rates than survivors. Hypersalivation was significantly more common in nonsurvivors (11/39; 26.8%) than survivors (1/39; 3%). Overall, 48.8% (39/80) of cats survived. When cats that were euthanatized without treatment were excluded from analyses, the survival rate was 66.1% (39/59). Pyothorax recurred in 1 of 17 cats for which follow-up information was obtained. CONCLUSIONS AND CLINICAL RELEVANCE: Cats with pyothorax that received treatment had a fair to good prognosis, with low recurrence rates in survivors. Hypersalivation and low heart rate were associated with worse clinical outcome. Cats with pyothorax were likely to come from multi-cat households.